/Engine/Source/Runtime/Landscape/Public/LandscapeSubsystem.h
Updates the Nanite mesh on all landscape actors whose mesh is not up to date.
void BuildNanite ( [TArrayView](API\Runtime\Core\Containers\TArrayView)< [ALandscapeProxy](API\Runtime\Landscape\ALandscapeProxy) * > InProxiesToBuild, bool bForceRebuild )